Resonant cavity strained group III-V photodetector and LED on silicon substrate and method to fabricate same

ABSTRACT

A structure includes an optoelectronic device having a Group IV substrate (e.g., Si); a buffer layer (e.g. SiGe) disposed on the substrate and a first distributed Bragg reflector (DBR) disposed on the buffer layer. The first DBR contains alternating layers of doped Group IV materials (e.g., alternating layers of SiyGe(1−y), where 0.8&lt;y&lt;1, and SizGe(1−z), where 0.2&lt;z&lt;0.4) that are substantially transparent to a wavelength of interest. The structure further includes a strained layer of a Group III-V material over the first DBR and a second DBR over the strained layer. The second DBR contains alternating layers of electrically conductive oxides (e.g., ITO/AZO) that are substantially transparent to the wavelength of interest. Embodiments of VCSELs and photodetectors can be derived from the structure. The strained layer of Group III-V material can be, for example, a thin layer of In0.53Ga0.47As having a thickness in a range of about 2 nm to about 5 nm.

TECHNICAL FIELD

The various embodiments of this invention relate generally tooptoelectronic solid state semiconductor devices and fabricationtechniques and, more specifically, relate to light emitting diodes(LEDs) and photodetectors (PDs) containing semiconductor materials andto the fabrication of such devices, and even more specifically relate tovertical cavity surface emitting lasers (VCSELs) and resonant cavity PDdevices.

BACKGROUND

Group III elements include Al, Ga and In; Group IV elements include C,Si and Ge; Group V elements include P, As and Sb. For Group III-V basedoptoelectronics such as lasers, LEDs and PDs, on Group IV (e.g., Si)substrates relatively thick layers (e.g., >1 μm) of Group III-V materialare needed to compensate for the typically high defect density at theinterface of Group IV and Group V material systems. It can bedisadvantageous both time-wise and expense-wise to epitaxially depositsuch relatively thick layers.

SUMMARY

In a first aspect thereof the embodiments of this invention provide astructure that comprises an optoelectronic device, comprising asubstrate that comprises a Group W semiconductor material; a bufferlayer disposed on the substrate; a first distributed Bragg reflector(DBR) disposed on the buffer layer, the first DBR comprised ofalternating layers of doped Group IV materials that are substantiallytransparent to a wavelength of interest; a strained layer disposed overthe first DBR, the strained layer being comprised of a Group III-Vmaterial; and a second DBR disposed over the strained layer, the secondDBR comprised of alternating layers of electrically conductive oxidesthat are substantially transparent to the wavelength of interest.

In another aspect thereof the embodiments of this invention provide amethod that comprises providing a substrate that comprises a Group IVsemiconductor material; epitaxially depositing a buffer layer on asurface of the substrate; depositing alternating layers of doped GroupIV materials on the buffer layer to form a first distributed Braggreflector (DBR) on the buffer layer, the alternating layers of dopedGroup IV materials being substantially transparent to a wavelength ofinterest; depositing a strained layer comprised of a Group III-Vmaterial over the first DBR; and depositing alternating layers ofelectrically conductive oxides over the strained layer to form a secondDBR over the strained layer, the alternating layers of electricallyconductive oxides being substantially transparent to the wavelength ofinterest.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIGS. 1-4 are each an enlarged cross-sectional view wherein the variouslayer thicknesses and other dimensions are not necessarily drawn toscale. More specifically:

FIG. 1 depicts an enlarged cross-sectional view of a conventional GroupIII-V based VCSEL;

FIG. 2 is an enlarged cross-sectional view of a VCSEL that isconstructed in accordance with embodiments of this invention to includea Group III-V light emitting layer in a resonant cavity structure on aSi substrate;

FIG. 3 is an enlarged cross-sectional view of a resonant cavity PD thatis constructed in accordance with embodiments of this invention toinclude a Group III-V light absorption layer in a resonant cavitystructure on a Si substrate; and

FIG. 4 is an enlarged cross-sectional view of a combination of the VCSELof FIG. 2 and the resonant cavity PD of FIG. 3 on a common Si substrate.

FIG. 5 is a fabrication flow diagram that is descriptive of a process toconstruct either the VCSEL of FIG. 2 or the resonant cavity PD of FIG.3.

DETAILED DESCRIPTION

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. All of the embodiments described inthis Detailed Description are exemplary embodiments provided to enablepersons skilled in the art to make or use the invention and not to limitthe scope of the invention which is defined by the claims.

The terms “epitaxial growth and/or deposition” and “epitaxially formedand/or grown” mean the growth of a semiconductor material on adeposition surface of a semiconductor material, in which thesemiconductor material being grown has the same crystallinecharacteristics as the semiconductor material of the deposition surface.In an epitaxial deposition process, the chemical reactants provided bysource gases are controlled and the system parameters are set so thatthe depositing atoms arrive at the deposition surface of thesemiconductor substrate with sufficient energy to move around on thesurface and orient themselves to the crystal arrangement of the atoms ofthe deposition surface. Therefore, an epitaxial semiconductor materialhas the same crystalline characteristics as the deposition surface onwhich it is formed. For example, an epitaxial semiconductor materialdeposited on a <100> crystal surface will take on a <100> orientation.In some embodiments, epitaxial growth and/or deposition processes areselective to forming on semiconductor surface, and do not depositmaterial on dielectric surfaces, such as silicon dioxide or siliconnitride surfaces.

Examples of various epitaxial growth process apparatuses and methodsthat are suitable for use in implementing the embodiments of thisinvention can include, but are not limited to, chemical vapor deposition(CVD) such as, for example, rapid thermal chemical vapor deposition(RTCVD), atmospheric pressure chemical vapor deposition (APCVD), lowpressure chemical vapor deposition (LPCVD) and ultra-high vacuumchemical vapor deposition (UHVCVD). Other suitable epitaxial growthprocesses can include, but are not limited to, molecular beam epitaxy(MBE) and low-energy plasma deposition (LEPD). The temperature for anepitaxial deposition process typically ranges from about 300° C. toabout 900° C. Although higher temperature will typically result infaster deposition of the semiconductor material, the faster depositionmay also result in crystal defects and film cracking.

Unless expressly indicated differently any references to a “top surface”herein imply a surface in a direction away from some surface that wouldsupport a substrate, while any references to a “bottom surface” imply asurface in a direction towards the surface that would support thesubstrate.

A distributed Bragg reflector (DBR) is a well-known type of structurethat can be formed from multiple layers of alternating materials withdifferent values of refractive index. This structure results in aperiodic variation in the effective refractive index. Each layerboundary causes a partial reflection of an optical wave. For those waveswhose vacuum wavelength λ, is about four times the optical thickness ofthe layers the multiple reflections combine with constructiveinterference and the layers thus function as a high-quality reflector.

The embodiments of this invention use only a relatively thin layer of astrained Group III-V material (e.g., a 2 nm-5 nm thick InGaAs layer) ina resonant cavity structure defined by a combination of an electricallyconductive first DBR comprised of alternating transparent layers of, forexample, Si and SiGe (more specifically alternating Group IV layers ofSi_(y)Ge_((1−y)), where 0.8<y<1, and Si_(z)Ge_((1−z)), where 0.2<z<0.4)and an electrically conductive second DBR comprised of an oxide such asalternating transparent layers of Indium Tin Oxide (ITO) and Al dopedZnO (AZO or Al:ZnO). The ITO can be composed of, as one non-limitingexample, 74% In, 18% O₂, and 8% Sn by weight. The Al dopingconcentration in the Al:ZnO can be in a range of about 0.5% to about 5%,with about 4% being one suitable nominal value. Using the thin layer ofstrained Group III-V material on a lattice mismatched Si substrate thephotodetection and light emission capabilities can be extended to longerwavelengths. The presence of the resonant cavity aids in enhancing thephotodetection and light emission characteristics using the thin layerof strained Group III-V material, which can be grown free of defects onSi.

In order to place this invention in a proper technological contextreference is first made to FIG. 1 for showing an enlargedcross-sectional view of a conventional Group III-V based VCSEL 1. Theconventional VCSEL 1 includes a GaAs substrate 2 and an overlying layern+GaAs buffer layer 3. Disposed on the buffer layer 3 is a bottom n-typedoped DBR 4 composed of alternating thin layers (nominally one quarterwavelength (λ/4) thick) of GaAs and AlGaAs. Disposed on the bottom DBR 4is a strained InGaAs quantum well (QW) light emitting layer 5 anddisposed on the QW light emitting layer 5 is a top p-type doped DBR 6also composed of alternating thin layers (nominally λ/4 thick) of GaAsand AlGaAs. In a typical embodiment whatever layer 4A (GaAs or AlGaAs)that lies beneath and supports the QW light emitting layer 5 is madesomewhat thicker, and a complementary AlGaAs or GaAs thicker layer 6A ofthe top DBR is disposed on top of the QW light emitting layer 5. TheVCSEL 1 is electrically connected to one or more n-contacts 7 (via thebuffer layer 3) and p-contacts 8. The VCSEL structure as shown can beconsidered as a p-intrinsic-n (P-I-N) diode where the bottom n-typedoped DBR 4 functions as a cathode, the top p-type doped DBR 6 functionsas an anode, and the QW light emitting layer 5 functions as theintrinsic (I) layer.

In the example depicted of the conventional VCSEL 1 the refractive indexof the DBR materials are GaAs: 3.6 and Al_(0.9)Ga_(0.1)As: 3.1. In thiscase the refractive index contrast=3.6/3.1=1.16.

FIG. 2 is an enlarged cross-sectional view of a VCSEL 10 that isconstructed in accordance with embodiments of this invention. It isnoted at the outset that the material compositions, numbers of layers,layer thicknesses and the like that are shown and described can varybased on intended design parameters and requirements. In thisnon-limiting embodiment the desired emission wavelength is acommunication-compatible wavelength in a range of about 1.3 μm to about1.65 μm and the material compositions and layer thicknesses and numbersof layers are set accordingly.

In this non-limiting embodiment the VCSEL 10 includes a Si substrate 12(e.g., a <100> Si substrate) having any suitable thickness. Disposed onthe Si substrate 12 is a relaxed SiGe (e.g., Si_(x)Ge_(1−x), where0.5<x<0.7) buffer layer 14 having a thickness in a range of about 100 nmto about 1000 nm. Disposed on the buffer layer 14 is a straincompensated p-type doped bottom DBR 16 composed of alternating Group IVlayers of Si_(y)Ge_((1−y)), where 0.8<y<1, and Si_(z)Ge_((1−z)), where0.2<z<0.4. In this non-limiting embodiment each of the layers of thebottom DBR 16 can have a thickness in a range of about 80 nm to about150 nm and there can be about 20 to about 35 pairs of the alternatingGroup IV layers of Si_(y)Ge_((1−y)) and Si_(z)Ge_((1−z)). The bottom DBR16 can be in situ doped p-type using, for example, Boron with a dopantconcentration in an exemplary range of about 10¹⁸ to about 10¹⁹atoms/cm³. A top-most Si_(y)Ge_((1−y)) or Si_(z)Ge_((1−z)) layer forms anominally thicker cap layer 16A.

Disposed on the cap layer 16A is, in this non-limiting embodiment, astrained InGaAs (e.g., In_(0.53)Ga_(0.47)As) light emitting QW layer 18having a thickness in a range of about 2 nm to about 5 nm and abandgap=0.75 eV. The InGaAs layer 18 is strained as it is grown directlyon the Si or SiGe cap layer 16A. In other embodiments of the inventionthe QW Group III-V layer 18 can be composed of, as several non-limitingexamples, binary Group III-V materials such as InAs or InSb, a ternaryGroup III-V material such as the layer 18 of In_(x)Ga_((1−x))As, where xis between 0.1 and 0.8, or a quaternary Group III-V material such as,for example, InGaAsP.

In FIG. 2 the InGaAs layer 18 functions as a light emitting layer sincein the final device it is operated as a forward biased p-n or p-i-njunction. In the photodetector embodiment described below in relation toFIG. 3 the InGaAs layer 18 functions as a light absorbing layer since inthe final device it is operated as a p-n or p-i-n reverse biasedjunction.

Disposed on a top surface of the Group III-V light emitting layer 18 isa Group III-V surface passivation layer 20 that, in this non-limitingembodiment, is embodied as a relative thin (e.g., about 100 nm to about300 nm) GaAs layer.

Disposed on a top surface of the Group III-V surface passivation layer20 is an electrically conductive oxide top DBR 22 that, in thisnon-limiting embodiment, is embodied as an ITO/Al:ZnO layer stack. Inother embodiments the top DBR 22 could contain, for example,electrically conductive oxide layers of TiO₂ or SnO₂:F. Sputtering andatomic layer deposition (ALD) are two exemplary methods of depositingthe electrically conductive oxide top DBR 22. The index of refraction ofthe top DBR 22 is less than the index of refraction of the bottom DBR 16and it can contain, for example, about 15 to about 25 pairs of ITO andAl:ZnO layers, where each of these layers has a thickness in a range ofabout 150 nm to about 300 nm. There can be p-contacts 24 coupled to thebottom DBR 16 via the electrically conductive buffer layer 14 andn-contacts 26 coupled to the top DBR 22. One or both of the contacts 24,26 could be ring-shaped contacts. The contacts 24 and 26 are connectedduring use to an operating voltage potential (e.g., in a range of about1.0V to about 1.5V). During operation light emission in the exemplaryrange of about 1.3 μm˜1.65 μm is directed vertically upwards from thetop surface of the top DBR 22. The combination of the layers 16A, 18 and20, or at least layers 18 and 20, can be considered as embodying anintrinsic region in a P-I-N light emitting diode.

The bottom distributed feedback reflector (DBR) 16, composed of thealternating Group IV layers of Si_(y)Ge_((1−y)) and Si_(z)Ge_((1−z))material, in one non-limiting embodiment if the invention exhibits arefractive index of, e.g., Si: 3.4 and Si_(0.2)Ge_(0.8): 4.1 and thushas a refractive index contrast equal to 4.1/3.4=1.21, a value that isbeneficially greater than the value of 1.16 for the conventionalGaAs/AlGaAs DBR 4 shown in FIG. 1.

The bottom DBR 16 composed of the alternating Group IV layers ofSi_(y)Ge_((1−y)) and Si_(z)Ge_((1−z)) and the top ITO/AZO DBR 22 areboth substantially transparent to light having a wavelength of interest,e.g., light having a wavelength in a range of about 1.3 μm˜1.65 μm inthis non-limiting example.

FIG. 3 is an enlarged cross-sectional view of a resonant cavityphotodetector (PD) 30 that is constructed in accordance with embodimentsof this invention. As with the VCSEL 10 the material compositions,numbers of layers, layer thicknesses and the like that are shown anddescribed can vary based on intended design parameters and requirements.In this non-limiting embodiment the desired absorption wavelength isagain the communication-compatible wavelength in a range of about 1.3μm˜1.65 μm and the material compositions and layer thicknesses andnumbers of layers are set accordingly.

It will be appreciated that the overall fabrication details and theresultant structure of the resonant cavity PD 30 can be the same or verysimilar to that of the VCSEL 10 of FIG. 1. One possible distinction isthat the optical requirements of the PD DBR can be somewhat less thanthose of the VCSEL DBR.

With this in mind, in this non-limiting embodiment the resonant cavityPD 30 includes a Si substrate 32 (e.g., a <100> Si substrate) having anysuitable thickness. It will be shown with respect to FIG. 4 that the Sisubstrate 32 can be the same substrate as the Si substrate 12 of FIG. 2.Disposed on the Si substrate 32 is, in one non-limiting embodiment, arelaxed Si_(x)Ge_(1−x), where 0.5<x<0.7, buffer layer 34 having athickness in a range of about 100 nm to about 1000 nm. Disposed on thebuffer layer 34 is a strain compensated p-type doped bottom DBR 36composed, in one non-limiting embodiment, of alternating Group IV layersof Si_(y)Ge_((1−y)), where 0.8<y<1, and Si_(z)Ge_((1−z)), where0.2<z<0.4. In this non-limiting embodiment each of the layers of thebottom DBR 36 can have a thickness in a range of about 80 nm to about150 nm and there can be about 20 to about 35 pairs of theSi_(y)Ge_((1−y)) and Si_(z)Ge_((1−z)) layers. The bottom DBR 36 can bedoped p-type using, for example, Boron with a dopant concentration in anexemplary range of about 10¹⁸ to about 10¹⁹ atoms/cm³. A top-most layerof Si_(y)Ge_((1−y)) or Si_(z)Ge_((1−z)) forms a nominally thicker caplayer 36A.

Disposed on the cap layer 36A is a strained Group III-V layer such as,in one non-limiting embodiment, an In_(0.53)Ga_(0.47)As QW layer 38that, in this embodiment, functions as a light absorption layer for thelight incident on the top surface. The In_(0.53)Ga_(0.47)As QW layer 38can have a thickness in a range of about 2 nm to about 5 nm and abandgap=0.75 eV. As was noted above for the VCSEL 10 embodiment of FIG.2, other Group III-V materials and concentrations can be employed.

Disposed on a top surface of the light absorption layer 38 is a GroupIII-V surface passivation layer 40 that, in this non-limitingembodiment, is embodied as a relative thin (e.g., about 100 nm to about300 nm) GaAs layer.

Disposed on a top surface of the Group III-V surface passivation layer40 is, as one non-limiting example, the ITO/Al:ZnO electricallyconductive oxide top DBR 42. Once again the index of refraction of thetop DBR 42 is less than the index of refraction of the bottom DBR 36 andit can contain, for example, about 15 to about 25 pairs of ITO andAl:ZnO layers/Each of these layers can have a thickness in a range ofabout 150 nm to about 300 nm. There can be p-contacts 44 coupled to thebottom DBR 36 via the electrically conductive buffer layer 34 andn-contacts 46 coupled to the top DBR 42. One or both of the contacts 44,46 could be ring-shaped contacts. The contacts 44 and 46 are connectedduring use to an operating voltage potential (e.g., a voltage in a rangeof about 0V to about −5V). During operation light received at the topsurface having a wavelength in an exemplary range of about 1.3 μm˜1.65μm is absorbed in the, for example, strained In_(0.53)Ga_(0.47)As QWlayer 38 and generates detectable charge carriers. The combination ofthe layers 36A, 38 and 40, or at least layers 38 and 40, can beconsidered as embodying an intrinsic region in a P-I-N light absorbingphotodetector diode.

As in the embodiment of FIG. 2 the bottom distributed feedback reflector(DBR) 36, composed of the alternating layers of Si_(y)Ge_((1−y)) andSi_(z)Ge_((1−z)), can exhibit a refractive index of, for example, Si:3.4 and Si_(0.2)Ge_(0.8): 4.1 and can have a refractive index contrastequal to 4.1/3.4=1.21. The bottom DBR composed of the alternating GroupIV layers of Si_(y)Ge_((1−y)) and Si_(z)Ge_((1−z)) and the top ITO/AZODBR 42 are both substantially transparent to light having a wavelengthof interest, e.g., 1.3 μm˜1.65 μm in this non-limiting example.

In the embodiments of this invention other types of layers/films canalso be included, such as an anti-reflection (AR) coating (not shown)that can be disposed on the top surface of the device.

FIG. 4 shows an embodiment of an optoelectronic transmit/receivestructure 50 that contains both the VCSEL 10 as in FIG. 2 and theresonant cavity PD 30 as in FIG. 3. The VCSEL 10 and the PD 30 share acommon Si substrate 52 and can share a common backside electricalcontact 54, typically a ground potential contact. The VCSEL 10 and thePD 30 are each fabricated within an aperture or well that is wet or dryetched into the substrate 52 and that is lined with a dielectric spacer56 (e.g., a nitride or an oxide having a thickness in a range of about10 nm to about 200 nm) to provide electrical isolation of the VCSEL 10and the PD 30 from the grounded substrate 10. The buffer layers 14 and34 (e.g., Si_(x)Ge_(1−x), buffer layers, where 0.5<x<0.7) can bedeposited on a bottom surface of their respective wells followed by theepitaxial growth of the overlying layers of the bottom Group IV DBRs 16,36, the strained Group III-V, e.g., In_(0.53)Ga_(0.47)As, lightemitting/light absorbing layers 18, 38 and associated GaAs passivationlayers 20, 40, and the overlying ITO/Al:ZnO electrically conductiveoxide top DBRs 22, 42. The annular ring-type contacts 26 and 46 can thenbe deposited to provide electrical top-side connections to the embeddedVCSEL 10 and PD 30. During use the optoelectronic transmit/receivestructure 50 is optically coupled to an end of an output optical fiber58 that receives, in this exemplary embodiment, the emitted 1.3 μm˜1.65μm light from the VCSEL 10 and to an end of an input optical fiber 60that provides, in this exemplary embodiment, 1.3 μm˜1.65 μm light to thePD 30.

In the embodiment of the optoelectronic transmit/receive structure 50shown in FIG. 4 the fabrication of the VCSEL 10 and the PD 30 can beaccomplished in parallel such as by the simultaneous deposition andgrowth of the various layers that are common to both devices.

It is pointed out that in addition to the VCSEL 10 and the PD 30 otherdevices and electronic circuitry including field-effect transistors,bipolar transistors, metal-oxide-semiconductor transistors, diodes,resistors, capacitors, inductors, etc., can be fabricated on or in thesame common Si substrate 52. In addition, the Si substrate 52 cancontain multiple VCSELs 10 and/or PDs 30 and these additionaloptoelectronic devices may all operate at the same wavelength or theymay operate at different wavelengths. For example, linear or twodimensional arrays of VCSELs 10 and/or PDs 30 can be provided on thesame common Si substrate 52 with additional support circuitry as needed.

FIG. 5 is a fabrication flow diagram that is descriptive of a process toconstruct either the VCSEL 10 of FIG. 2 or the resonant cavity PD 30 ofFIG. 3 (or both in the embodiment of FIG. 4). A first step 5A provides asubstrate that comprises a Group IV semiconductor material. A secondstep 5B epitaxially deposits a buffer layer on a surface of thesubstrate. A next step 5C deposits alternating layers of doped Group IVmaterials on the buffer layer to form a first DBR on the buffer layer. Anext step 5D deposits a strained layer comprised of a Group III-Vmaterial over the first DBR. A further step 5E deposits alternatinglayers of electrically conductive oxides over the strained layer to forma second DBR over the strained layer.

In the method the step of depositing the strained layer comprises anadditional step of depositing a Group III-V passivation layer on thestrained layer, and the step of depositing alternating layers ofelectrically conductive oxides deposits them on the Group III-Vpassivation layer.

In one non-limiting embodiment of the method the substrate is comprisedof Si, epitaxially depositing the buffer layer deposits a relaxed SiGelayer, such as a Si_(x)Ge_(1−x) layer, where 0.5<x<0.7, having athickness in a range of about 100 nm to about 1000 nm, and depositingalternating layers of doped Group IV materials on the buffer layerdeposits alternating Group IV layers of Si_(y)Ge_((1−y)), where 0.8<y<1,and Si_(z)Ge_((1−z)), where 0.2<z<0.4, where each layer has a thicknessin a range of about 80 nm to about 150 nm and where there about 20 toabout 35 pairs of the alternating Group IV layers of Si_(y)Ge_((1−y))and Si_(z)Ge_((1−z)) that are deposited. In this non-limiting embodimentof the method the step of depositing alternating layers of electricallyconductive oxides over the strained layer deposits alternating layers ofIndium Tin Oxide (ITO) and Aluminum doped Zinc Oxide (AZO), where eachlayer of ITO and AZO has a thickness in a range of about 150 nm to about300 nm and where there about 15 to about 25 pairs of the ITO and AZOlayers that are deposited. In this non-limiting embodiment of the methodthe wavelength of interest is in a range of about 1.3 μm˜1.65 μm andwhere depositing the strained layer comprised of a Group III-V materialdeposits a layer of strained InGaAs, such as but not limited to a layerof In_(0.53)Ga_(0.47)As, having a thickness in a range of about 2 nm toabout 5 nm.

An integrated circuit in accordance with the present invention can beemployed in applications, hardware, and/or electronic systems. Suitablehardware and systems in which such integrated circuits can beincorporated include, but are not limited to, personal computers,communication networks, electronic commerce systems, portablecommunications devices (e.g., cell phones), solid-state media storagedevices, functional circuitry, etc. Systems and hardware incorporatingsuch integrated circuits are considered part of this invention. Giventhe teachings of the invention provided herein, one of ordinary skill inthe art will be able to contemplate other implementations andapplications of the techniques of the invention.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

As such, various modifications and adaptations may become apparent tothose skilled in the relevant arts in view of the foregoing description,when read in conjunction with the accompanying drawings and the appendedclaims. As but some examples, the use of other similar or equivalentsemiconductor fabrication processes, including deposition processes,etching processes may be used by those skilled in the art. Further, theexemplary embodiments are not intended to be limited to only thosematerials, metals, insulators, dopants, dopant concentrations, layerthicknesses and the like that were specifically disclosed above. Any andall such and similar modifications of the teachings of this inventionwill still fall within the scope of this invention.

What is claimed is:
 1. A structure comprising an optoelectronic device,comprising: a substrate that comprises a Group IV semiconductormaterial; a buffer layer disposed on the substrate; a first distributedBragg reflector (DBR) disposed on the buffer layer, the first DBRcomprised of alternating layers of doped Group IV materials that aresubstantially transparent to a wavelength of interest; a strained layerdisposed over the first DBR, the strained layer being comprised of aGroup III-V material; a second DBR disposed over the strained layer, thesecond DBR comprised of alternating layers of electrically conductiveoxides that are substantially transparent to the wavelength of interest;and a passivation layer disposed on the strained layer disposed over thefirst DBR, the passivation layer being comprised of GaAs.
 2. Thestructure as in claim 1, where the first DBR is comprised of alternatinglayers of doped Si and SiGe.
 3. The structure as in claim 1, where thefirst DBR is comprised of alternating Group IV layers ofSi_(y)Ge_((1−y)), where 0.8<y<1, and Si_(z)Ge_((1−z)), where 0.2<z<0.4.4. The structure as in claim 1, where the first DBR is comprised ofalternating layers of p-type doped Si_(y)Ge_((1−y)), where 0.8<y<1, andSi_(z)Ge_((1−z)), where 0.2<z<0.4, where each layer has a thickness in arange of about 80 nm to about 150nm and where there about 20 to about 35pairs of the alternating layers of Si_(y)Ge_((1−y)) andSi_(z)Ge_((1−z)).
 5. The structure as in claim 1, where the second DBRis compriSed of alternating layers of Indium Tin Oxide (ITO) andAluminum doped Zinc Oxide (AZO).
 6. The structure as in claim 1, wherethe second DBR is comprised of alternating layers of Indium Tin Oxide(ITO) and Aluminum doped Zinc Oxide (AZO), where each layer has athickness in a range of about 150 nm to about 300 nm and where thereabout 15 to about 25 pairs of the ITO and AZO layers.
 7. The structureas in claim 1, where the substrate is comprised of Si, and where thebuffer layer is comprised of SiGe.
 8. The structure as in claim 1, wherethe substrate is comprised of Si, and where the buffer layer iscomprised of a relaxed Si_(x)Ge_(1−x) layer, where 0.5<x<0.7, having athickness in a range of about 100 nm to about 1000 nm.
 9. The structureas in claim 1, where the strained layer comprised of a Group III-Vmaterial has a thickness in a range of about 2 nm to about 5 nm.
 10. Thestructure as in claim 1, where the strained layer comprised of a GroupIII-V material is a light emitting layer at the wavelength of interestand has a thickness in a range of about 2 nm to about 5 nm.
 11. Thestructure as in claim 1, where the strained layer comprised of a GroupIII-V material is a light absorbing layer at the wavelength of interestand has a thickness in a range of about 2 nm to about 5 nm.
 12. Thestructure as in claim 1, where the wavelength of interest is in awavelength range of about 1.3 μm to about 1.65 μm.
 13. The structure asin claim 1, where the wavelength of interest is in a wavelength range ofabout 1.3 μm to about 1.65 μm, where the strained layer comprised of aGroup III-V material is comprised of a strained In_(0.53)Ga_(0.47) Aslight emitting layer at the wavelength of interest having a thickness ina range of about 2 nm to about 5 nm.
 14. The structure as in claim 1,where the wavelength of interest is in a wavelength range of about 1.3μm to about 1.65 μm, where the strained layer comprised of a Group III-Vmaterial is comprised of a strained In_(0.53)Ga_(0.47) As lightabsorbing layer at the wavelength of interest having a thickness in arange of about 2 nm to about 5 nm.
 15. The structure as in claim 1,where p-contacts are coupled to the first DBR via the buffer layer. 16.The structure as in claim 15, where the p-contacts are ring-shaped. 17.The structure as in claim 1, where n-contacts are coupled to the secondDBR.
 18. The structure as in claim 17, where the n-contacts arering-shaped.
 19. The structure as in claim 1, where the strained layercomprised of a Group III-V material is a binary arrangement of GroupIII-V materials or a quaternary arrangement of Group III-V materials.